18 thoughts on “Cellphone Ring Notifier

  1. put you cell phone on vibrate and lay it on a stand alone piece of metal, if done right it’ll resonate so loud you could hear it from anywhere in the house, trust me it happened in school once.

  2. That looks like a cool hack but instead of using light detection it would be much cooler to detect the radio waves emissions around the cellphone during an incoming call, you wouldn’t have to put the cell in a box like this guy did either.

  3. Spiffy, but I’d like to expound on the first part of the topic–what makes that pen-sized cell phone call notifier work? I’ve been looking for an explanation for a while, but I haven’t found anything reasonable for an answer.

  4. The op amp or the coil detect cell phone waves, i.e. radio frequancy radiation. More likely though, the coil response to the cell phones bigger antenna/coil going off, and being more sensitive, it goes off sonner and more often.

  5. apparently coming up with a reasonable solution to a simple problem is out of the question (philip) — something that plagues many developers in general.

    What would be much more interesting (and much less practical… in the useful sense of the word) would be if someone built something sensitive enough to be able to detect phone calls in… for example a movie theatre — and, for the purposes of practical jokes, made certain that the whole theatre would know…

  6. Of course those would be more practical alternatives, in much the same way that building a computer using a computer box is more practical than fitting it inside a novelty lamp, and buying a nightvision scope from your friendly neighborhood militia nutjob or on Ebay is more practical than scavenging parts for a homemade one. The point is that it’s cool that he did it.

  7. Who ever said hackers are rational/sensible/conservative/practical/sane/etc people?
    Pragmatism before principle.
    And the value of your own hard work is always better then the prettyness of commercial bought items. Besides, a Minty mp3 might be less purty then an iPod, and cost more (then the shuffle at least for full new parts) but being able to say I built an mp3 player from scratch makes the attention you get from cute h4

  8. Radioshack used to sell a “wireless mailbox alert”

    It was pretty useless for urban area where your mailbox is a 1/2 mile away, but it detected the light from someone opening the mailbox and sent a signal to a receiver that would have a light and alert that the mail had come.

    I have one at home, and it may work perfectly to hack into a similar modification.
    The bonus is the connection to the phone would be wireless and compact.

    Here is a similar product:

    Also after owning several “ring detectors” that work off radio, I can ensure you they are worthless. The pen I owned didn’t work with my cellphone, but it randomly vibrated at anytime due to other RF signals.
    The flashing model I bought for my car would flash randomly also, but did at least work with my cellphone.

  9. Or if you’ve got a GSM phone (or any modern digital phone) the radiation will be of the right band to directly interfere with any speaker (remember to turn off cellphones when recording with microphones as it interferes with those too). So just leave the thing near a speaker (even an answering machine speaker works)/stereo/radio. There will be a telltale rhythmic buzzing whenever there’s network activity (switching towers or the beginning of a phone call) and then the speakers will buzz constantly about 1 second before the phone actually rings.

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